Well swab cup



June 1969 c. H. COLLETT 3, 50,412

WELL SWAB CUP Filed March 20, 1967 INVENTOR. 09442555 A. (@44677 Ma/xix.

United States Patent 3,450,412 WELL SWAB CUP Charles Haskell Collett,P.0. Box 411, Menlo Park, Calif. 94025 Filed Mar. 20, 1967, Ser. No.624,350 Int. Cl. F16 15/48; B61f 15/22 U.S. Cl. 277212 11 ClaimsABSTRACT OF THE DISCLOSURE A well swab cup with a molded nylon cagehaving cupreinforcing fingers.

The present invention relates to well swabs and more particularly to aswab cup of novel construction composed of a molded nylon cage or innerreinforcement on which is molded a cup-like body of rubber.

In the construction of well swab cups it is common practice to mold arubber cup-like body with an internal reinforcing cage typically havinga metallic ring or base thimble which supports a plurality ofcircumferentially spaced spring wire fingers. In use, one or more ofsuch cups are disposed upon a swab body or mandrel which is adapted tobe connected to a swab line to be run into a well. Fluid in the well,herein generally referred to as well fluid, including oil, water, mud ora combination of such fluids, will bypass the cup or cups as they movedownwardly in the well, through the cups and around the cups, as well asthrough the supporting mandrel in the case of a valved mandrel. However,when the swab assembly is retrieved from the well, the bypass of wellfluids i stopped and the cup is caused by hydrostatic pressure actingthereon to expand into tight sealing and sliding engagement with thewell pipe Ibeing swabbed.

Of course, in 'deep wells especially, the cup is subjected to severewear conditions, depending upon the weight of the column of fluid beinglifted by the swab, as the cup slides within the well pipe, and thereinforcement in the cup is adapted to protect the cup against wear aswell as against being turned inside out or torn off of the mandrel.

While wire reinforcement fingers have been in long use they have notbeen altogether satisfactory due to the tendency of the rubber cups totear from the wire fingers when the cup is heavily loaded and due to thetendency of the wire fingers to more or less locally flex into slidingcontact with the well pipe, thereby causing undue local wear andultimate failure.

The present invention, therefore, has an object the provision of a novelswab cup construction which includes a molded resilient plasticreinforcing cage which includes fingers spaced cirou-mferentially aboutthe cup and defonrnable with the cup so as to engage the well pipe andreinforce the cup, the fingers having flexing characteristics compatiblewith the rubber cup and being wear resistant when in sliding engagementwith the pipe.

Another object is to provide a well swab cup reinforcing cage havingunitized base and finger sections adapted to have a rubber body moldedthereon, and the finger section thaving integral elements which serve tomaintain the relative spacing of the fingers during the moldingoperation.

Still another object is to provide a well swab cup having a moldedplasitc reinforcing cage including circumferentially spaced fingerswhich adjacent their free ends are united by frangible elements, wherebyto enable outward flexure of the upper margin or sealing lip portion ofthe cup when the swab assembly of which the cup forms a part is movedupwardly in the well pipe to be swabbed.

Other objects and advantages of the invention will be hereinafterdescribed or will become apparent to those ice skilled in the art, andthe novel features of the invention will be defined in the appendedclaims.

In the accompanying drawing:

FIG. 1 is a view showing in side elevation a swab cup made in accordancewith the invention and mounted upon a swab mandrel so as to be run intoa well pipe shown in vertical section;

FIG. 2 is a view in trainsverse section through the swab cup of FIG. 1,on the line 22;

FIG. 3 is a view in longitudinal section as taken on the line 3--3 ofFIG. 2, and showing in broken lines the loaded condition of the cup inthe well pipe;

FIG. 4 is a fragmentary view in section, as taken on the plane of FIG.2, but showing the finger connecting elements broken following initialloading of the cup; and

FIG. 5 is a view in perspective showing the molded plastic careconstruction, with certain of the repetitive elements broken away.

Like reference characters in the several views of the drawing and in thefollowing description designate corresponding parts.

Referring first to FIG. 1, there is shown a swab cup S disposed on amandrel M including a bottom guide 1 of any suitable construction andhaving an upper seating surface 2 engageable by the swab oup S when wellfluid is being lifted from the well pipe, such as tubing 0r casingdesignated C. Customarily, the swab cup S is free to move on mandrel Mso that as the assembly is being lowered in the pipe C, the cup S willbe off of the seat 2, thereby allowing fluid to pass between the cup andthe mandrel. In addition, the mandrel may have a passage therethroughhaving a check valve to allow the passage of well fluid therethrough'during downward movement of the swab assembly while closing the passageas the swab assembly is being retrieved from the well to lift a columnof fluid from the pipe C.

Typically, swab cups of the type here involved comprise a body ofelastomeric material, generically referred to as rubber, reinforced witha cage of wire springs or the like to prevent the rubber body fromrapidly wearing and being destroyed by the heavy pressure appliedthereto by the column of fluid being lifted from the well pipe.

Accordingly, the present swab cup S comprises a rubber body having alower rigid seating section 4, an intermediate main section 5 and anupper relatively resilient sealing lip section 6. Within the cup body isa reinforcing cage R, which, in accordance with the invention, is ofunitary molded plastic construction. Preferably, the plastic cage iscomposed of nylon or other durable and wear resistant trnold ableplastic.

The reinforcing cage R includes an annular base section 7 within thelower cup section 4, a plurality of ciroumferentially spaced elongatefingers 8 disposed in the intermediate cup section 5, and on alternatefingers re: duced section finger tips 8a which extend upwardly into thesealing lip section 6 of the cup body.

The base section 7 of the cake is downwardly tapered on its outer face,and on its inner annular face is provided with a rigid metal thimble 9turned outwardly at 10 at its upper end to provide a flange and notchedat 11 to interlock the thimble with the plastic cage during molding ofthe cage. The thimble 9 is adapted to prevent substantial outwarddeformation of the cup section 4, and if desired the outer portion ofthe cup base may be further supported by an outer metal thimble in acustomary manner. The rubber material at the base section 4 of the cupcovers the cage base 7 inside and outside and provides a seal portion 12sealingly engageable with the seating surface 2 of the guide nut 1 onthe mandrel M. The fingers 8 extend upwardly and slightly divergentlyfrom the base 7 of the cage R substantially to the lip section 6 of thecup body, and the rubber material fills the spaces between the fingersand covers both the inner and outer surfaces of the fingers.

At the sealing lip portion of the cup the finger tips 8a on alternatefingers 8, in the illustrative embodiment, form extensions of the innersurfaces of their respective fingers, but have a thickness or crosssection less than the fingers. T'he finger tips 8a terminate within thesealing section 6, which provides a substantial annular rubber sectionadapted to establish initial sealing contact with the well pipe. Sincethe finger tips 8a are comparatively small in cross section, the sealinglip portion 6 of the cup may readily expand or flex outwardly underpressure to effect such initial sealing engagement. Moreover, suchresilient flexing is enhanced by the fact that the finger tips 8a are ononly certain of the fingers 8, in the illustrative cage R on alternatefingers.

As best seen in FIGS. 3 and 5, the cage fingers 8 adjacent their upperends are provided with means normally holding them in predeterminedspaced relation. This means comprises frangible webs 8b molded betweenthe fingers during molding of the cage. Preferably, the webs 8b bridgethe outer peripheries of the fingers. Such webs serve to not only fixthe spacing of the fingers during molding of the rubber body on thecake, but also to establish the diameter about the fingers, therebyfacilitating manufacture.

When the swab cup is in use, it will understood that the pressure actinginside the cup cavity will force the sealing lip 6 into :light sealingengagement with the pipe as the swab is being retrieved. In addition,the intermediate section of the cup will be deformed, approximately asshown in broken lines in FIG. 3, so that the frangible webs will bebroken to allow outward flexure of the reinforcing fingers in the cup.At their upper ends, the fingers 8 are bevelled at 8c at such an angleas to assist in causing the cup to flex inward when passing thedownwardly facing pipe shoulder in the usual casing joints, as shown inFIG. 1.

Under heavy fluid loads, the fingers 8 will bend substantially in therubber body so as to move outwardly toward the pipe wall. However, nylonfor example has a good recovery rate and the cup will return to itsoriginal form after use to enable reuse through a substantial number ofruns under ordinary well pipe and other environmental conditions.

After a certain amount of use, the rubber covering the fingers 8 will beworn away, exposing the outer faces of the fingers. Another advantage ofnylon or the like fingers is that they will be wear resistant andrelatively friction free, thereby enhancing the life and utility of thecup.

Moreover, when the fingers 8 are exposed following wear of the outerlayer of rubber, the plastic material will not under any circumstancescause sparking when engaged with dry pipe adjacent the top of the well,where oxygen may be present to support combustion of gases in the pipe.

I claim:

1. A well swab cup comprising: a cup-like body of elastomeric material,a reinforcing cage molded in said body, said cage being composed ofresilient plastic material and having a unitized annular base with aplurality of circumferentially spaced fingers extending upwardly fromsaid base.

2. A well swab oup as defined in claim 1, wherein said body has asealing 'lip portion projecting beyond the ends of said fingers andcertain of said fingers have finger tips extending into said lipportion.

3. A well swab cup as defined in claim 2, wherein said finger tips areof reduced section relative to said fingers.

4. A well swab cup as defined in claim 2, wherein alternate fingers havesaid finger tips.

5. A well swab cup as defined in claim 1, wherein said cage is composedof nylon.

6. A well swab cup as defined in claim 1, wherein said reinforcing cageincludes a rigid metallic thimble disposed within said base.

7. A well swab cup as defined in claim 1, wherein said fingers areprovided with means bridging said fingers and holding the same inpredetermined spaced relation.

8. A well swab sup as defined in claim 7, wherein said means bridgingsaid fingers comprises integral webs on said fingers.

9. A well swab cup as defined in claim 7, wherein said means bridgingsaid fingers comprises integral webs on and bridging the outsides ofsaid fingers.

10. A well swab as defined in claim 7, wherein said means bridging saidfingers comprises frangible webs integral with said fingers adjacenttheir outer ends, and certain of said fingers having finger tipsprojecting beyond the other fingers.

11.. A well swab cup as defined in claim 1, wherein said fingers attheir upper ends are provided with a bevelled surface extending inwardlyand upwardly.

References Cited UNITED STATES PATENTS 1,548,580 8/ 1925 Christensen92-241 1,563,164 11/1925 Christenson 92-241 1,767,936 6/1930 McElroy etal. 277-231 X 2,336,090 12/1943 Granger 92-241 2,358,908 9/ 1944Crickmer 92-241 2,581,981 1/1952 Taylor 92-241 X 2,852,323 9/ 1958Bowerman 92-241 X 2,887,347 5/1959 Losey 92-241 3,094,904 6/ 1963 Healy92-241 3,152,809 10/ 1964 Waldrop 277-212 3,346,267 10/ 1967 Farley277-233 X CARROLL B. DORITY, Jr., Primary Examiner.

US. Cl. X.R.

